Antimicrobial Properties of Microparticles Based on Carmellose Cross-Linked by Cu2+ Ions

Carmellose (CMC) is frequently used due to its high biocompatibility, biodegradability, and low immunogenicity for development of site-specific or controlled release drug delivery systems. In this experimental work, CMC dispersions in two different concentrations (1% and 2%) cross-linked by copper (II) ions (0.5, 1, 1.5, or 2.0 M CuCl₂) were used to prepare microspheres with antimicrobial activity against Escherichia coli and Candida albicans, both frequently occurring pathogens which cause vaginal infections. The microparticles were prepared by an ionotropic gelation technique which offers the unique possibility to entrap divalent copper ions in a CMC structure and thus ensure their antibacterial activity. Prepared CMC microspheres exhibited sufficient sphericity. Both equivalent diameter and copper content were influenced by CMC concentration, and the molarity of copper (II) solution affected only the copper content results. Selected samples exhibited stable but pH-responsive behaviour in environments which corresponded with natural (pH 4.5) and inflamed (pH 6.0) vaginal conditions. All the tested samples exhibited proven substantial antimicrobial activity against both Gram-negative bacteria Escherichia coli and yeast Candida albicans. Unexpectedly, a crucial parameter for microsphere antimicrobial activity was not found in the copper content but in the swelling capacity of the microparticles and in the degree of CMC surface shrinking.